Earlier forms of freestanding ladder structures are commonly made of wood, fiberglass, reinforced plastic or aluminum. Typically, linear pieces of uniform cross section are joined to form a suitable frame. Sometimes, many pieces of material and hardware are needed just to form a single part of the ladder. This labor extensive process can be expensive. A further disadvantage is that an extra manufacturing step is required for each feature such as hooks, nonslip tread, color, graphics and directions.
U.S. Pat. No. 4,023,647 describes a ladder that overcomes some of foregoing deficiencies by providing a freestanding pool ladder that is constructed of plastic and formed by the process of blow molding in this method the entire ladder section of the structure is blow molded as one piece.
Unfortunately, this method provides limited structural rigidity. Thus, reinforcing inserts, such as wood, must be arranged within areas of high stress.